Custom PCB Design for Calculator

Thought for 6 sec

I’m blocked from modifying the project right now because execution credits are unavailable, so I can’t add components or generate the schematic directly in Flux yet.

What remains to be done:

Rename the placeholder project and create a short project specification.
Add the ESP32 NodeMCU DevKit V1 CP2102 module, SSD1306 OLED connector/module, 50 tactile switches, I2C pull-up resistors, and any recommended support parts.
Verify the ESP32 DevKit and OLED pinouts against datasheets/module documentation before wiring.
Build the keyboard as an optimized matrix, likely 7 rows × 8 columns = 56 possible keys, using 15 GPIOs for 50 switches.
Avoid ESP32 boot strapping pins GPIO0, GPIO2, GPIO12, GPIO15 for keyboard scan lines.
Connect OLED I2C:
- SDA → GPIO21
- SCL → GPIO22
- SDA pull-up → 4.7 kΩ to 3.3 V
- SCL pull-up → 4.7 kΩ to 3.3 V
- OLED VCC → ESP32 3.3 V
- OLED GND → common GND
Connect all switch matrix return paths to common ground reference through the ESP32 system ground.
Run schematic review/ERC after wiring and fix any unresolved issues.
Stop before PCB routing, per your request.

Recommended ESP32 pin allocation for the 50-key matrix, avoiding the restricted boot pins:

Table

Matrix Line	ESP32 GPIO
ROW0	GPIO13
ROW1	GPIO14
ROW2	GPIO16
ROW3	GPIO17
ROW4	GPIO18
ROW5	GPIO19
ROW6	GPIO23
COL0	GPIO25
COL1	GPIO26
COL2	GPIO27
COL3	GPIO32
COL4	GPIO33
COL5	GPIO34
COL6	GPIO35
COL7	GPIO36

Important note: GPIO34, GPIO35, and GPIO36 are input-only pins on the ESP32, so they are suitable as column inputs but not row outputs. The firmware should scan rows as outputs and read columns as inputs with pull-ups/pull-downs handled appropriately. Since GPIO34–36 do not have internal pull-ups, external pull-up resistors may be needed on those column lines unless the chosen DevKit/module already provides suitable biasing.

Generate 7x8 schematic

Add column pull-ups

Create key map

Check GPIO conflicts

Run ERC review

No schematic yet

Talk to Flux to get started.